Progress towards a vaccine against onchocerciasis
TOVA has its origins in the river blindness (onchocerciasis) vaccine program of the Edna McConnell Clark Foundation (EMCF) that contributed $21.6 million between 1985 and 1999.
This investment focused on:
- development of experimental animal models for screening candidate vaccine antigens
- analysis of immunological mechanisms evoked by immunization with protective recombinant vaccine antigens
- identification of protective antigens
When the programme ended, the work of African, American and European laboratories had developed three animal models, identified a portfolio of 15 O volvulus vaccine candidates including eight that were tested in the O ochengi bovine model, and obtained proof-of-principle of vaccination against infection ()Table 3).
The impetus given by EMCF was carried forward by the European Union through its Directorate-General for Research and Innovation (FP5, VARBO; FP6, SCOOTT; FP7, E PIAF, Enhanced Protective Immunity Against Filariasis, coordinated by Professor David W Taylor), and by the US NIH National Institute of Allergy and Infectious Diseases (The development of a recombinant vaccine against human onchocerciasis, headed by Dr Sara Lustigman).
The work of these programmes:
- increased the understanding of the epidemiology and pathology of onchocerciasis
- helped define the mechanisms of protective immunity against filarial parasites
- demonstrated the role of parasite-induced immunomodulators in expression of protective immunity
- identified three candidate vaccine antigens that have proven to be efficacious in three different filarial animal model systems and in five independent laboratories.